Radio broadcast distributing system



.June 5, 1928.

- E. E. CLEMENT RADIO BROADCAST DISTRIBUTING SYSTEM Original Filed 001;. 28, 1924 'ZSheets-Sheet 1 June 5, 1928.

\ E. E. CLEMENT RADIO BROADCAST DISTRIBUTING SYSTEM Original Filed Oct. 28, 1924 7 Sheets-Sheet 2 7 O v 1 T N E M E L C .E .& 2 9 l 5 m J RADIO BROADCAST DISTRIBUTING SYSTEM Original Filed Oct. 28, 1924 7 Sheets-Sheet 3 m N NTMWWN \MB wk m m X oNNw 9w m6 R i N V @H NW N %N June 5, 1928.

E. E. CLEMENT RADIO BROADCAST DISTRIBUTING SYSTEM Original Filed Oct. 28, 1924 '7 Sheets-Sheet 4 E. E. CLEMENT,

June 5, 1928.

RADIO, BROADCAST DISTRIBUTING SYSTEM Original Filed Oct. 28, 1924 '7 Sheets-Sheet 5 June 5; 1928. 1,672,407

E. E. CLEMENT RKDIO BROADCAST DISTRIBUTING SYSTEM v Original Filed Odt. 28, 1924 7 Sheets-Sheet 6 June 5, 1928. 1,672,407

E. E. CLE MENT RAD'IO BROADCAST DISTRIBUTING SYSQTEM ori inal Filed Oct. 28, 1924 'T SheetS-Sheet 7 on: M

TIME-U DURATION MILY DESPA STATION A RtMAl K6 ROUTE srmou REMARKS DMLY DES PATCH SHEET REMARKS) Patented June 5, 1928.

UNITED STATES PATENT OFFICE-Q EDWARD E. CLEMENT, OF WASHINGTdN, DISTRICT OF COLUMBIA, ASSIGNOR TO EDWARD F. OOLLADAY, OF WASHINGTON, DISTRICT OF COLUMBIA.

RADIO BROADCAST DISTRIBUTING SYSTEM.

Original application filed October 28, 1924, Serial No. 746,357.

Patent No. 1,635,153, dated July 5, 1927.

Divided and this application filed May 2, 1925. Serial No. 27,514.

My invention relates to systems of radio broadcast distribution, and the present application is a division of my prior c0pending application, filed October 28, 1924: Serial No. 746,357 Patent No. 1,635,153, issued July 5, 1927. This invention has for its object to provide an organization for the broadcasting of intelligence in which orderly distribution may be secured, with maximum efiiciency, and the entire service may be metered, whether local or long distance.

By means that will be described, it is contemplated to have national district and local programs made up day by day, from which any subscriber my select. Selection 15 determined by frequencies, which by the use of double modulation may be frequencies of the envelope or intermediate wave transmitted. At present not more than five such frequencies will probably be required for this purpose, although many more are available in the present state of the art, and the numher will probably be increased as development proceeds.

Following the plan laid down in my preceding application, Serial No. 581,829 Patent No. 1,522,357, upon which Reissue No. 16,231 was granted Dec. 15, 1925, all supervision, metering, testing, and the like, which are individual to the subscriber, are done locally, that is to say, over the subscribers telephone wire and either at his local telephone exchange, or at a local radio exchange associated therewith.

Certain lines of apparatus are developed and described in this specificatioinwhich so far as possible have been limited strictly to present standards of practice. It is to be understood that these are used for purposes of definition only, and not of limitation. Thus, while the entire system is built up of vacuum tube receiving and transmitting sets, other means may be substituted if and when the same becomes suiliciently reliable to meet the public need. All other changes and modifications which do not depart from the spirit of the invention are to be considered as contemplated thereby and included therein.

My invention is illustrated in the accompanying drawings, in which Fig. 1 is a graphical diagram showing the channels of distribution and lines of au thority and control in the system.

Fig. 2 system. v,

Fig. 8 is a diagram of a telephone central station with two subscribers stations connccted to it and is intended to be read with Fig. 4 is a continuation of Fig. 3, and shows a radio central station and a radio subscribers station physically connected therewith through the telephone circuits of Fig. 3.

Fig. 5 is a diagram showing the subscribers double detector receiving set of Fig. tdivided into two single demodulating units, one located at the subscribers station and the other located at the-central oflice, the first detector being at the subscribers station and sending long waves through the subscribers line to the second detector at central, which sends back audio waves to the subscribers telephone.

is a circuit diagram of the same Fig. 6 is a diagram showing a further modification oi the circuit of Fig. 5, in which regeneration is added, at the subscribers sta tion, and the intermediate wave line coupling at central is included in the cord circuit.

Fig. 7 is a diagram of a further modification showing the said cord circuit provided with the same elements'as in Fig. 6 except the battery which is in two units, one for talking and telephone signaling, and the other for the detector tube plate circuit.

Fig. 8 is a diagram showing a simplified form of metered system.

Figs. 9, 10 and 11 show respectively the daily program despatch sheet for the master or A station, a B station in the eastern time division and a local or C station inthe same time division.

Referring to Fig. 1, the station A is shown connected by lines of distribution to'district stations B, B B and B. The stations B are in the eastern division, the stations B in the central division, the stations B in the mountain. division, and the stations 13* in the coast division. Each of these district stations is shown connected by lines of distribution to local distributing stations C in its district, and each of these local stations is shown connected to stations I) typifying the ultimate subscribers stations. The lines of distribution also repre sent telephone trunk lines from C stations to B stations. D represents the subscribers equipment, like the stations B and C.

telephone lines which either terminate in Stations C (if they are identical with telephone exchange stations), or are connected thereto, as indicated in Figs. 3 and 1.

It will be noted that in Fig. 1 not all the stations B are connected to station A by di rect individual trunk lines, but some district stations trunk through a district master station, thus economizing trunk lines. Thus, the trunks 58, 59, and 60 in Fig. 1 are shown extending to master district; ations in the groups B B and B respectively, other B stations in these district groups being con nected to A through the respective master stations B by relatively short trunk lines 61, 62 and 63. The number and routing oi. trunks so used is of course variable, and may be accommodated to the necessities oil telephone traflic so as not to interfere with the normal telephonic use oi the wire plant, which is one of the cardinal points in the design of the present system.

A better idea of the general arrangement of circuits symbolized in Fig. 1 is conveyed by Fig. 2, wherein a subscribens line 18-19 (see Fig. 3) extends from his station A to the central telephone exchange C which is equipped with line jacks J, connecting plugs PP and trunk jacks J From the trunk jack J shown. in the figure, a trunk line 50 extends to the district station B. which is also equipped with switchl'ioard terminals including plugs P"-P and trunk jacks 1 J From the jack J shown in the figure a trunk 51 extends to the master station A where it terminates on a jack J. The station is equipped with plugs P P and may be fully provided with telephone switching Details of such switching equipment are shown. in Figs. 3 and 4. In Fig. 2 operators telephone instruments are shown at 81, 82 and 83, connected in the usual manner to the cord circuit, and these symbolize a complete signaling and supervisory system. Each operator at stations B and A. also has a demodulator and receiver for long 1F waves. with suitable key for controlling the connection of the same to her cord circuits.

The radio equipment of station C includes a relay receiver and transmitter T with a local microphone and amplifier I for local modulation. The antenna symbolized at 52 is supposed to receive waves sent out from the B station of the district in which the particular station (1 happens to be located, and to which it is connected by means 01 the trunk line 50, which of course does not symbolize all telephone trunks but only such as may be allotted for the so-called radio traftic. The frequency to which the antenna circuit 52 is tuned in that allotted to the 0 stations and to which they are all normally or permanently tuned. The antenna circuit 53 is for radiating modulated carrier waves to the subscribers D in the particular local area surrounding and served by the station C under consideration. The frequency to which the antenna is tuned is that allotted to the subscribers D, and to which they are all normally or permanently tuned. The details of the subscribers station apparatus, in cluding both telephone and radiophone are shown in Figs. 3 and 1, wherein a particular station of class D is designated as A, and will be described hereinafter.

Gbviously, performances, or news, or other items of varied character which it is desired to broadcast either locally or over this entire system may be picked up in any part of the same, and since it would be impossible to bring all artists, to, or tooriginate all matter at, the station A, there must be provision for ingathering as well as for distribution. or, stated in another way, the system must be flexible enoughto permit broadcasting from any part of it. It may be assumed therefor, without attempting to arbitrarily settle details ot' ultimate practice, that all studio and other connections for broadcasting, should initially be made through a C station. Theoretically any subscrihers station having a telephone transmitter may thus become a broadcasting station, as disclosed in my prior copendi'ng application, Serial No. 746,357, Patent No. 1,635,153, hereinbe't'orc referred to. Practically. while the subscribers stations may be used as pickups. regular studio work will probably always be done either through P B X boards with special equipment. or in other special stations connected with a C central station. All of these may be taken as symbolized by the station D or A. in Fig. 2.

It should be noted in passing that this 1110- cation or original modulation to C stations does not interfere with direct broadcasting from or B stations. since each of these can most conveniently be located at and operated in conjunction with a telephone central exchange which is also a C station or has a C station connected to it, as shown in Figs. 3 and 4.. Thus in Fig. 1 I have shown a microphone transmitter 64 at every station of the orders A, B. and C. to indicate that broadcasting may be originated thereat when required. The actual manner in which this is now intended to be done is shown in Fig. 1. The symbolic station 0 is provided with a pair of jacks J and J between which are connected the audio amplifier 65 and the intermediate frequency modulator and oscillator transmitter (56. The jacks J and J may be connected through the operators cords and plugs with the line jack .l on the one hand and with either one of the jacks J or J on the other. Ii jacks J and J are plugged together and jacks J and J are plugged together, then the operation would be as follows: Assuming the till 1 presently described.

subscriber A to" transmit soundi waves" eleetricatlly" overhis line IS -19 these waves pass into the: audio" amplifier 65" and thence into. the'mo'dulator 66; whereby a modulated intermediate frequency carrier wave-recommunicated tothe input sideof the relay transmitter T which in'turn' modulates the-- long wave thus produced upon theshort carrierw-ave allotted" to stations'D, and=radiates the same from theantenna 53. the station G is broadcasting on the common frequency Wave, sing an intermediate frequency which the subscribers 1 can receive by double demodulation,

Now: assume that instead of jacks J and J being;pluggechuptogether; the jacks' J and J are so connectedi The-result will be a's-follows'z The audioWaves-over'line 18419 pass to the-'- audio' amplifier 65 and thence to the-modulator and oscillator transmitter'tv'ti by means} of which an. audio modulated intermediate frequency carrier current is transmitted over t'hetrunkline to the station B. At this station an arrangement of jacks' is encountered similar to that at station C. Jacks J and J have connected between them an intermediate frequency or carrier amplifier 67: Whichunaybe plugged up' either for broadcasting from the antenna orfor continued transmission over the trunk 51't-o the station A. To produce the first result, jacks J G and J are plugged together and jacks J 9 and J are plugged together, whereupon the carrier current or intermediate frequency carrier waves will be communicated to the input circuit of'the oscillator transmitter B and thereby modulat'ed ona high frequency carrier wave radiated from the antenna 55, at stand ard C frequency. 'I his \\-*ave-' will be received and may be relayed by all the C stations within range of the transmitting station B If wider distribution be desired thejaelr J is' plugged ontothe jack- J of the trunk line 51, and the amplified or re layed intermediate frequency cara'er Waves as that'of the amplifierG'i at station B5 By plugggingiup' the ack- J to the jaclif J2 th amplified intermediate frequency" waves will be communicated tothe input side of the-oscillator transmitter '1 and thereby inodulated on a short carrierwave and radiated from the antenna 57. this wave has a frequency allotted t'o the B stations; all' the B stations will receive it, and may in turn relay it to= the" C stations and they in 1 turn relay it to" their subscribers. One reason for the rule that all broadcast matters shall originateat orthrough-a- C station Wlll n'ow' be apparent, viz that the initial audio or telephone Waves may bechanged as near'as Thus in a manner to be possible to'the' point of origin to modulated intermediatefrequency carrier VSVBS, which inay'th-en be imposed as modulations on a radiatedcarrier, oron a wire circuit, with equal eliiciency. Audiowaves in a wire circuit are subject to distortion to agreaterdegree than modulated superaudio frequency carrier. Waves. Also, by using supe-raudio frequency currents on the trunklines, ad.- vantage can be'taken .of the well established systems of multiplexing and relaying already inuse, and the trunks rendered more productive Without interfering with their'telephonic use. Thus, the initialaudio waves are alwaysc'hanged into'modulated superaudio Waves'at the nearest central sta tion, and thence dispatched either on a carrier-wave radiatedfroni an antenna, or on a trunk wire'tosome other point where they are so dispatched. In order to add'still further to theflexibility of the system, theA station at the right of Figure 2 may trunk from a jack or: aclrsJ through a trunk or trunks designated as X to any other part of the system. as ior example to a particula Bstation, where the trunk X may terminate on a jack similar to J for connection toradio transmitter T. or by further trunkingto some particular C station, and so to-thera-dio transmitter T at such station, whereby matter can be picked up at'any pointand broadcast either generally or in a selected'district or in a selected local area only'. It follows also from this arrangement that when' radio transmission is difficult over long; distances or in any particular section of the system; due to seasonal or diurnal or non-periodic phenomena, the" distribution by wire can madeto supplement distribution by pure f dio and the'average of efficiency maintained throughout the'syste'm. To accomplish this every part of the system must cooperate per fectly With all other parts as determined by." the master control station A" and district master control stations B! B", etc. both in time of transmission and ma iiiten ance of'clcar transmission channels. Such coordination may be compared to the 1cm of train-dis patching on a railway they use of interlocking records and. time sheets, for A. B and C stations. and the management and dispatching of all radio traffic by a regular tral'lic force trained for that purpose. Tofiilly understandthis idea. the

operating organization must be considered for amoment, First it mu e taken into account that this SZVSi'QHLClL not contemplate uncompensated or irregular use of telephone trunks and wire plant. but on the contrary based on the assumption that the telephone con'ipanies. by contract or other.- wise. will have a participi tinginterest in all earnings of the radio broadcasting system, if they do not collectively act to operate it. The use of all wires andswitching equip stem, and involves nient will. therefore be paid for, and the cost of the service with a suitable profit Will be distributed over the entire body of subscribers, and regularly collected by the local cental station authorities by flat rentals or toll charges, both of which are herein provided for. Owing to the character of much of the work involved in oi ierating, such as gathering, collecting, editing and allocating, the material to bebrc-adcast as well as the attendant work or despatching and supervisingthe distribution of the daily program over theconntry, all of which is foreign to the normal service. activities of a telephone organization, it would appear necessary to have a special operating organization, embracing the following: (1) Reporting and editorial ClQPttUlTll'lEIlt; (2) contract department, for artists and. crnitributors; cugineering dcpartn'ient, for regulation of methods and standardizing of apparatus, to work in conjunction with telephone engineering staff; 1) operating department, in cluding routing, despatching and supervision; (5) business department, to receive and handle all matters of accounting, and in cooperation. with the telephone organization, to fix charges.

Referring to Figs. 3 and l: have therein shown circuits of the central office and substation equipments and COI'iiiQCiliOHS, Fig. 3 representing the telephone side of the temrand Fig. 4 the radiophone side of the system. Before proceeding to detail description it may be noted that in accordijince with standard telephone practice, [)lOVlPlOi'l is made for keeping the telephone lines and central office circuits clear of all grounds or other disturbing connections during conversation. When the radiophone goes into service, by closing the filament switch its operation in receiving is identical with that of any radio receiver, and .in the event that use is made of any transmission of waves over theline wires, as will be hereinafter pointed out, said transmission will be at a frequency above the limits of audition. diagram, I have shown the circuits arranged with. nothing but continuous current for radio purposes over the telephone line wires. This is the simplest form of control and the one nearest to present-day telephone practice, and isabso-lutely certain not to produce any disturbance in adjacent conductors in the telephone cables. Each radiophone set is provided withv a cut oil relay energized when the telephone set goes into comn'iission, either by calling or being called, and at the central. otlice whenever the radio operator takes con trol of the line, he disables it in the usual manner by pulling up the cut off relay at the telephone switchboard, this however being subject to the condition that a. special tone test may be put on the radio board, and subject to interruption for telephone conanswering plug.

t iple taps marked 16, 17?, and 1'7", and

19 19". These terminate on i'nultrple jacks" in the present and A are two subscribers stations connect ed by line wires 1617 and 1 -l9re pectively to the central station 0 wiere they terminate on. acks J and J. .P are plugs forming the terminals of a cord circuit 20 21, 22-23, having a bridged repeating coil I, the usual ringing and listening keys, supervisory signals .v.s" and bridging connection to the main battery B. The same battery is'shown supplying current to the line relays L, L, and through contacts at the cut off relays L If to the respective lines for calling purposes. in this sy: em, when a subscriber takes down his receiver, the line relay lights its lamp, which is eX- tinguished when the operator inserts the Battery supply for the connected lines is thereafter taken through the cord circuit 2(l22, 9 1 23,,in a. mani'ier well understood in the art. When the substation telephones are out of service, with their receivers hanging on their books, the line circuits are conductively open for direct. current, leaving the ringers Q, and Q in circuit for alternating ringing current pass ing through the condensers Referring now to Fig. l. it will be observed that the radio switchboard which I have designated, generally by the letter R, is coniiected to the subscribers lines by mul J J corresponding to the multiple .iaclrs on the telephone switchboard. it should be noted that throughout this Tystein the tip wires 16 and 18 with their branches are connected to ground, while the sleeve wires 17 and 19 and their branches, areconnected to battery. This is extended into the radio side of the system for the purpose of securing proper balance-between the main battery or power plant. of that side and the main battery or power plant of the telephone side of the system.

At the subscribers stations taps are also taken off from the telephone terminals to the radiophone terminals as indicated at 18, 19, and 19. (The radiophonc is shown only at one substation for sake of simplicity of illustration) .The two branches i9" and 19 are taken from the sleeve orbattcry side of the line 19. and a re connected to o 'i 'iositc terminals of the winding of a relay L, which constitutes the substation cut otf relay for the radiophone' The windin of this rclav is bridged by a condenser through which inter- I both ringing and voice currents can pass Without substantial impedance. Where the radiophone is attached to a party line substation, this relay L may be omitted, since on such party lines there are u ually grounds on one side or the other.

Normally, that is to say, when the telephone circuit is not in use, the cut oft relay L is deenergized and a consequence the wire 19 is connected through a back contact of the relay through extension wire 24 to the branch 25 connected to the A battery marked A, in F The wire 18 similarly passes through a back contact ot the relay to the extension wire 26 leading totest or listening relay QT and ground. 18, itv will be remembered, leads to the tip or ground side of the line, therefore it is the side which in the radiophone can be made usev of with a pernninent ground or grounds, without disturbiiiig the balance of the telephone circuit.

The ratliophonereceiver at the substation A is shown as comprising an antenna 28,

tuned coupler 29, first detector tube 30, tuned lilter coupler 33, second detector 31, audio amplifier tube 32, and audio transformers 34, 85, the last mentioned transmitting the amplified audio waves to the telephone receiver or loud speaker 36. I The filament battery is A The plate battery is B, and suitable tuning condensers and coils, tickler coil for regenerativeetl'ects, etc., are provided as-required. I should remark in passing that this representation of the radio receiver is intended to be typical only.

The relay L has four pairs of contacts, one pair 27* closing the wires 25 and 37 from battery A, to the filaments. The second pair 27' closes the wires 25 and 38 was to put battery A, on the telephone transmitter T. and through the induction coil 1, to ground. The third and fourth pairs oft contacts 27 27, close the wires 39 and 40, forming terminals of the secondary induct-ion coil circuit 1, to the tip and sleeve side of the telephone line respectively, through the back contacts of relay L Tue transmitter T is shown hanging upon a hook switch H controlling the connection of wires 41 and 42, constituting a parallel link between the battery A, and the filament bus 43. Thus the tilanient can be heated and the radio phone put in service either through the agency of the relay L or by the switch hook H. The former is controlled by the radio operator at centrahand the latter by the subscriber at the substation. In addition to the hook, the subscriber has a manual switch it by which he can connect the battery, wire 42 through a wire 44 to histransmitter T, coil and. ground, so as to energize his talking circuit. 1 provide an ordinary telephone receiver Z" in series with the secondary ot' the induction coil 1, and I interpose a pair of condensers 9* between the second- Returning now to the central station, and

particularly .to the radio department thereof shown in Fig. 4, T represents a broadcasting transmitter, symbolized in very simple form, but supposed to contain the usual elements of power supply, modulator, oscilla tor and aerial, with suitable amplification of the, audio ,waves supplied on the input side. The jack J connected to the amplifier 25 and thence to the transmitter T, symbolizes a group of such jacks or equivalent connecting means such as automatic switches, controlled by dials or keys for connecting any of the wire lines to said radio transmitter. Detailed appliances, both for the switching and for the radio transmission, are well known in the art. and need no specific description, my present invention having to do particularly with the method of transmitting by Wave radiation to the substations, and of bringing in all conversation originating or received at the substation radiophone'over the subscribers Wire line. This includes repetition of modulated radio waves received at the radiophone substation and also originating messages gathered up and to be put through the amplifier t on the transmitting T for broadcasting.

The cord circuit between plugs P and P in Fig. 4 is the same as the operators cord circuit in Fig. 2, but the radio operator also hasspecial test cords such as that shown in the upper part of the ligureconnected to plug P. Here the keys KK are of stand ard construction, as in the other cords, and the test contact of the plug P" is connected through. suitable resistance to the supervisory lamp 5 to the radio battery B, means such as the commutator p being provided to give special tone test on the test thim- Lies of the multiple jacks J, J, J etc. Itwill be observed that the constant connection of the sleeve or battery wire 24 at the radiophone substation to the bus wire 25 of the battery A produces charging of that battery by the constant flow of current therethrough from the main radio battery E at the central ,oflice. The amount of energy thus delivered to the battery A depends uponthe size of the line wires, and the length of time available for such charging. As shown, the. battery wire 24 is not cut oil except when the cut oli relay L pulls up which is only when the line wire is in use for conversation.

tions from the IF waves.

In Figs. 3 and 4;, it has been assumed that the subscriber would employ apparatus for demodulating double modulated carrier Waves, including two detector tubes, the first of which takes off the intermediate frequency carrier waves upon which the audio modulations are imposed; and the second of which takes 011' the audio frequency modula- It is desirable to lessen the amount of apparatus at the subscribers station, and at the same time give the central office operators an opportunity to supervise by listening in on any message being received, and to meter the service in simple and efficient manner. For these purposes, I have shown in Figs. 5, 6 and T demodulating units located in part at the subscribers station and in part at the central station, the operation being for the subscribers unit demodulator to take off the modulated long or intermediate frequenc waves and transmit them over his line wires to the central officewhere they are further demodulated by a cord circuit unit which is plugged on his line, (orthe equivalent automatic switching apparatus). The second demodulator sends back audio frequency currents over the line wires to the subscribers station, where they affect lis ordinary telephone or any special form of receiver, including a table talker or loud speaker.

Referring to Fig. 5, the subscribers station A is equipped with a radiophone re ceiving device including an antenna circuit 28, tuned as usual, and coupled by means of coils 29 to the input side or grid circuit 125126 of the detector tube 85. The in put circuit may be tuned by means of condenser 129, but it is to be understood that this condenser and also the tuning elements in the antenna circuit may be adjusted once for all if the subscribers all work on a constant frequency, as hereinbefore set fortl'i. The plate circuit 127-128 of the tube includes one winding 128 of a tuned filter coupler, the other side of which 121 is connected to extensions 18 and 19 of ti subscribers telephone line circuit 18-19. The coil 123 is shunted by a condenser 12 1, and the capacity and inductance are so adjusted that the short circuit thus formed is resonant to the intermediate frequency Wa ves imposed on the short carrier Waves reaching the sub scribers instrument through the antenna 28. The variable condenser 122 is included in series with the coil 121, because of the line connection, tuning of the line being accomplished at both ends as will presentl appear.

At the central office, the line wires 18*19 are connected to any desired number of answering and multiple jacks typified bv the single jack J, and is provided with extensions 1819 passing to the radio department or radio switchboard R in the upper in Fig. 3, are intended to be interconnected with other jacks for telephonic purposes through a standard cord circuit 2021, 22-23, having terminal plugs P P, and bridged by a common talking and signaling battery B, feeding through the two halves of repeating coil I and also feeding through a ring on each plug and test thimble on each jack to the cut oii relaycircuit 19*, so that whenever a plug is in a jack of the line 18-19, circuit from battery. to the cut off relay L will be completed and the line relay L with its connection to the main battery B Will be cut off and removed entirely from the line. In this cut off portion of the cord circuit are inserted supervisory lamp signals, ss, adapted to be shunted by contact.-. controlled by supervisory relays cluded in the conductors 22-23, respectively. These relays respond to current in the subscribers lines when they are interconnected. and the lamps light When the subscribere hangup their receivers.

On the radio switchboard R, the same line is provided With jacks typified by jacks JJ As shown, these are in pairs, for convenience only, and to avoid putting a large-number of contacts in one jack. The upper jack J is a duplicate of the telephone jack J, and has its contacts connected in parallel to the same conductors, respectively. Jack J is a radio jack pure and simple, and is connected to the same line wires 1819 through a tuned filter coupler composed of coils 115 and 117 and con denser-s 116 and 118. The elements 115 and 116 are employed in conjunction With the elements 121 122 at the subscribers station to tune the line circuit to resonance at the frequency of the long waves sent forward as demodulated by the subscriber. The ele ments 116117 at central are included in this figure between the line and the jack because by this means the t'uning of the line can be made constant and adjusted once for all. The cord circuit adapted to. cooperate with these twin jacks has corresponding twin plugs P 'li preferably connected mechanically so they can be inserted and re moved from'the jacks at the same time. The plug P is the terminal of a standard talking circuit -91, with battery B bridged across it through coils 929 3, and provided with supervisory lamp 101, the controlling shunt therefor 102, the supervisory r lay 103 and the talking shunt there for 104;, also with special test coil 106 sup plied with a radio tone test through wire 108 from the commutator 107. hen this plus; is inserted in the jack J the cut off relay L of the telephone line is pulled up and the line cleared from all telephone switchboard connection, for radio use.

The plug P forms the terminal of a ra-v dio detector circuit, the tip and sleeve of the plug being connect-ed through conductors 9697 with the. grid and the filament respectively of the detector tube 86. The

plate. circuit 9798 of this tube isconnected to the outside terminals of coils 9 1-95 which with the bridged coil 92-93 form the usual repeating coil connection between two.

pass condenser 100.

The result of this arrangement is as fol lows: The subscriber calls for radio service by moving his switchhoolt at station A, up and down rapidly. This flashes the line lamp before the telephone operator, who thereupon inserts the twin plugs P -P into the jacks (F -J This pulls up the cut off relay L clears the line through from the substation to the cord circuit 90*91, 9G97, and thereupon, assum g that the subscriber has closed his filament circuit at the substation, radio waves received on his antenna 28 are demodulated, and their long wave or intermediate frequency component, carrying the audio modulations, is transmitted to line through the filter coupler 121-123. From line it passes through the filter coupler 11511'T and through the wires 9697 to the grid circuit of the tube 86; The varying potentials thus produced in the grid circuit of the tube are reproduced in current changes in the circuit 97-95 B 9 198. The superaudio frequency waves are absorbed by the circuit 99 and the condenser 100, and oure audio frequency waves are propagated through the repeating coil 9a95-9293, into the telephone line circuit, through the plug P, the jack J muliple wires 18 -19', and line circuit 1819, at the subscribers station these audio waves may bereceived on his ordinary telephone receiver a, or upon any special form of receiver desired.

Referring now to Fig; 6, I have shown therein a modification of the circuit of Fig. 5, in which the following features are introduced: First, I provide a feed back coil or tickler 130 at the subscribers station: a special receiving telephone 1.33 with a terminal plug 132 adapted to be inserted in the jack 131 bridged across the telephone line outside of the filter coupler 121-123; and lastly I have removed the central otlice lil ter coupler 115117 from its position be tween the line and the jack J as in Fig. and instead thereof have located this coupler in a bridge of the cord circuit 96 9'7. thus doing away with the twin plug P and its connections. This also reduces the num ber of couplers required, and most impor tant of all enables the complete radio cord circuit to be used with any ordinarytele phone jack, since the terminal plug P is an. ordinar tele hone terminal ')lu For the reason stated, I have designated both jacks in this figure by the letter J, the lower one being at the telephone switchboard and the upper one at the radio switchboard. Both may be used interchangeably,

or an' ordinary telephone si'vitchboard may be used for radio purposes without any change otherthan adding the filter coupler, the detector tube, and other connections to an ordinary standard answering plug cord. This interchangeability of the parts, makes it possible to give radio service on any telephone switchboard, using the same opera-- tors if desired, for both services. It also makes it possible to lengthen the life of a telephone switchboard, by rewiring the cords and converting it into a radio switch board.

In Fig. 6', the antenna circuit 28 and the coupler 29 are the same as before; the grid circuit is 125-126, the plate circuit 1272-128 includes a tickler coil 130, and the other parts have been referred to. At the central station the plug P is connected in Fig. 5 to the repeating coil, battery, supervisory lamp, controlling relay therefor, tone test,

etc. The coil 115 of the central office filter coupler is bridged across the terminals of the plug, with its tuning condenser 116 The twin member of the filter coupler 117, with its shunting tuning condenser 118, is bridged through conductors 9697 across the grid circuit terminals of the tube 85. The plate circuit 9T98 is connected to the repeating .coil in the cord, and in this case also includes a ti'ckler coil 134:, which maybe cutin and out of the plate circuit at will bymeans of a switch 98. feeds back into the grid circuit waves at intermediate frequency, as received over the line, and is intended to give a'higherratio of amplification in the audio current returnedto the subscriber than would be possible without it. It should be noted however, that instead of thus using the regenerative principle,I contemplate employing radio and audio amplification in one or more stages of each, inserted between'the detector tube '86'and the plug P or P (Fig. 5).

In Fig. 7 I have shown a modification of the cord, circuit in Fig. 6, which consists in providing a separate battery B forthe plate circuit 97-418 of the tube. This battery is located exit to the plate, and the by-pass condenser 100 is bridged across the terminals of the repeating coils 9l95. This appreaches more nearly to the common or standard method of connecting circuits than the bridge circuit of Figs. 56, and while probably not more eflicient, is a little more flexible, as it permits thevoltage of the B This coil battery to be varied at will, without reference to the voltage of the battery B which according to telephone practice is constant at about 22 volts. Thus if amplifier tubes are used between the lube S6 and the coils 91-95, a separate plate battery would be required for the amplifiers, giving a higher voltage according to common practice. The operation of Figs. 6 and 7 is as'tollows: The subscriber may call as before and in re sponse to his call the radio operator gives him a. cord circuit with terminal plu P or P, whereupon his unit through the detector tube 85 demodulates the short wave carrier received on antenna circuit 28, and sends the intermediate or long wave modulation thereof through the line wires to central, where it passes to the jack J and the plug P and is repeated by the tuned filter coupler 115- 117 into the grid circuit 96-97 of the tube 86. Through this tube, and any amplifying tubes which may be employed, the audio modulations are first detected and then amplified and sent back through the repeating coil to the plug P and the jack J to the subscribers line. At the subscribers station they are received either on his regular telephone receiver, or on the special telephone 133 which typifies any kind of receiver which it may be found expedient and desirable to employ.

In the drawings, Figs. 5, 6, 7, l have not shown any amplification, but it is to be understood that any desired amount of amplification may be added between the detector tube Stl nd the repeatin coils 9 l95. Such amplification may be o'lt any known or suitable type, and needs no illustration. The cord circuits shown in Figs. 5, 6, 7'however, with or without amplification, and thus adapted to give different classes of service, may be divided into groups, for which the subscriber should be charged different rates, as in long distance telephone service. It is very necessary that there be metering upon which to base the charges, since the service a time service and not a message service. For this purpose I. contemplate including in each cord a meter actuator such as g in Fig. 5, which will operate the subscribers line meter 301, which may be his telephone meter or a separate meter as desired, a number of times per hour determined by the class of service he is receiving. Thus the No. 1 cord circuit may be connected to a commutator that closes the line meter circult once every hour; No. 2 may have a meter actuator that works twice every hour; No. 3 may have an actuator that works three times in the hour; while No. t may have its actuator work every ten or twelve minutes. The reason for s-i'elccting these time divisions is that the average charge per message for telephone service is about five cents. At five cents per hour,'and averaging three hours service per day, a subscribers radio bill would be $4.50 per month. This is fairly comparable to the earnings of an average residence telephone for the same period, on a message rate basis. The fractions of time could not be out below a five cent value, unless a separate radio meter be provided for each line and it is desired to avoid this expense, as well as the upkeep of one hundred per cent of additional meters. In prior copending applications Serial No. 581,831, filed August 14, 1922, Patent No. 1,522,359, granted Jan. 6, 1925, and Serial No. 583,560, tiled August 22, 1922, Patent No. 1,522,367,

granted Jan. 6, 1925, I have shown and described metering systems which are suitable for use with the system of circuits herein disclosed, and in another application filed October 28, 192 1, Serial No. 746,358, based upon the same system of circuits herein dis clOsOd, I have disclosed and shall claim the adaptation o1 these metering circuits to the present system.

it should be particularly noted, that a subscriber, (which term is meant to include any v..er) may not keep his radiophone in "e a full hour, a pertinent example being that of a man who desires to obtain a baseball score or other special information. A special provision should be made for registering such service, as it involves all the elements of expense to the operating com pany which would be included in a much longer connection. For this purpose the operator may have a push button 9 connecting the actuating generator G direct to the meter circuit through'the plug P as shown in one form in Fig. 5, together with the automatic actuating means for the meter, comprising the commutator g which at stated intervals connects the generator G to the wire 297 leading to the third contact on the plug P which when the plug is inserted in jack J completes the circuit from wire 297 through wire 298 to the cut off relay wire 19, thence to the high winding 299 oi? the meter LM. In Fig. 5 the meter is shown as the ordinary standard telephone line meter, which would thus serve a double purpose, registering both the telephone calls and also the time of radiophone use in terms of telephone call units or telephone message units. Sucha meter by reason of the high resistance in its winding 299 will not re spond to the battery current which energizes the cut oflf relay L, but when the operator connects a generator as G producing current of higher voltage, then the meter magnet becomes sufliciently energized to attract its arn'iature and close the circuit of its low winding 300, the rush of current through the low winding producing strong and cer-. tain actuation of the meter countingdevice 301.

By thus having the operator always press thekeys 9 immediately after making a radiophoneconnection, there will alwaysv be made the commutator close the actuating circuit immediately afterward, the meter would register two units for the first hour of use. If it should happen that the subscriber hang up in fifteen minutes the line would still hear the. charge of two units for one hour. On the other hand", the connection was made immediately after the con'miutator had closed the metering circuit, then no additional charge would be made for an hour, and if thev subscriber should hang up within less thanv an hour, he would have only the one charge against the line. in. any event, the charge would be safe to the company and fair to the subscriber as all public service corporations make a service charge if the measured. rate charged is below a minimum amount. A commutator individual to each cord started when the cord is connected would. of course register individual time use only.

The system shown in Fig. 8 is the same as that ofFigQh but simplified by omitting the. radio broadcast distributing switchbo a-rd,.'giving the subscrioer a simple radio receiving set of the single tube regenerative type and giving the telephone switchboard operator control of the metering of broadcast. service.

Referring to the system of Fig. 8 more indetail the subscribers broadcast receivin 7 D set consists of a single tube radio receiving set BS of standard type with a set of head phones HT, and with no physical connection with the telephone line, but located at the substation A for use by the subscriber thereat. The subscribers substation telephone apparatus-and its line terminal apparatusL J, etc. are the same as that of Fig. except that the multiples 18 19 and 19* extend only to other telephone multiple switchboard jacks, not shown, according to usual' telephone practice. The operators cord circuit terminating in the plugs P, P"

isthe same as that of Fig. 5 except that it is provided with a second metering key TM "Which is a telephone service metering key for actuating the line meter Lh/I without actuating the cord circuit meter PM, the meter PM being used in this arrangement to rec- 0rd the use of the cord circuit for broadcast service. This use of the plug in connection with broadcast service consists in the connection of asubscribers line, such 18-19 of the substation A, through the cord circuit 2021, 22-23 to a program announcement jack PJ conected with the program bus PB which is supplied continuously with telephonic announcements of program items available to the subscribers at their radio receivingsets Winch announcements carry with them the proper instructions for tuning the: subscribers instrument.

Inoperatioma subscribe-r desiring broadcast service so apprises the operator by rapidly raising and lowering his switchhook which causes his line lamp L" to flicker and so immediately and directly indicate to the operator the character of. service wanted,v

whereupon the operator inserts the plugs P and. P in the jacks J and PJ' respectively, connectingthe subscriber to the progran'i bus PB The subscriber now receives, through his ordinary telephone receiver a, the an-' immediately tune in on the desired program item Without having to hunt and listen through parts of many different programs inorder to get the particular item or items desired.

Each time the operator establishes an ordinary telephone connection she makesv one momentary closure of the telephone meter key 'llyfwhich actuates. the subscribers line meter TQM to register one call, and each time a connection for. program service is made she closes the broadcast service. key g which actuates. both the line meter LM and the program service meter PM to register one unit charge thus charging the subscriber and recording the special service use of the cord circuit. This enables the telephone exchange company to give metered broadcast service to the subscribers without physical connection of broadcasting apparatus to the telephone circuits, to keep a record of the total amount of such special service rendered and to meter the service to the subscribers individually.

The station A can either broadcast direct or by wire trunking through the B stations, preferably the head B station of each division. It is further to be noted that the A station When so working over wire trunks can receive the same Waves radiated from B or antenna 56 (Fig. l) and by demodulating and the listening to the audio frequency com.- ponent thereof can determine the eiiiciency of transmission and the tuning of the B apparatuswith respect to the short carrier Wave employed.

Each station B is supposed to be a district station, that is, it compiles and checks up all bookings or regular number items in its district, keeps the A station informed thereof, makes up district programs, superlocal or C programs including items to be recorded and released later, receives, records and forwards traffic reports and charges from its district to A and acts. as a relay station for mixed Wire and radio transmission between the C stations in its district and the rest of the system. The relationof the B and C stations to each other and their operation will be better understood after an explanation of the last sheet of drawing herein, containing Figs. 9, and 11, as well as a statement of the manner of employing primary and intermediate frequencies for distribution without interference. First, however, the functions of the C stations should be fully understood. These are the stations which come into immediate contact with the subscriber, and which for transmission purposes form their immediate source of supply. So far as the general broadcasting goes, these stations will be largely considered as they are described in Patent No. 1,522,357, viz as relay or dis tributing stations, each for its own local area. In speaking generally of these stations it will be understood that they may or may not be identical with the telephone central stations for the same areas. In the majority of cases each radio C station will be one of a group of telephone exchange stations in its area, and will receive communications from all parts of the area except its own particular territory, by trunking. As there are approximately 10,000 telephone exchanges in the United States, of which approximately 5,000, it may be estimated, will be available as C stations in this system, the importance of having them properly organized and related to eachother as well as to the subscribers will be apparent. The functions of each radio exchange C include the following: Relay broadcasting on the subscribers or D carrier wave frequency of program items originating at B or A stations; selection of items and arrangement of local progran'is to include approved local items if any; listening in and supervising reception by subscribers, using the wire lines for this purpose; connecting subscribers wires or studio wires to trunk lines for direct communication or preferably through amplifier modulator and transmitter units and 66, for superaudio carrier current transmission over trunk lines 50 or to local broadcasting transmitters T as indicated in Fig. 1; rendering special service by broadcasting out with wire return, for special groups of subscribers holding meetings and the like, using special carrier-wave frequencies, or special intermediate frequencies for this purpose; metering all service, regular or special, and billing same, preferably through the financial department of the associated telephone operating company, installing, inspecting, testing and maintaining subscribers station equipment; and compiling, editing and publishing in the press, by wire, and otherwise, of the radio programs for the local area served.

A brief review of these functions will showthe advantage in reduction of expense and added ei'ticiency to both the telephone:

amount to $40,000 per month or $480,000

per annum. The costof labor for performing the functions mentioned would be many times this amount, sothat by the use of the system herein set forth, it may be estimated that several million dollars per annum of overhead expense will be saved, as compared with separately operated systems, or" to put it another way the wire plant will show. a large addition to its earnings by the reduction of overhead, entirely aside from direct payment for the radio service. If we assume a district with one B station and 99 C stations located therein, serving approximately 100,- 000 subscribers, the combined saving on overhead, without any direct earnings, would amount to more than $125,000 per annum, which while perhaps insuflicient to pay interest on the capital invested in broadcasting apparatus, would carry all ordinary expense of broadcast operation.

For the selection of items and arrange ment of local programs, the operation of C would be regulated according to 'ly dispatch sheets of the A and B statirms, (st-e Figs. 9 and 10) and the num ber of primary or intermediate frequencies avaiiahle, which will be presently explained. For listening in and supervising reception by the subscribers, the radio station C Dittllts' use the apparatus shown in Fig. 1, wii relay the waves radiated from the trans mitting station ma y be caused to return after demodulation over the wires so as to be audible to the operator through a proper listenq apparatus. The apparatus of Fig. 4 also a elements such V, P etc., for test-Inglhe subscribers line and instrument. lf loral batteries are employed at the subscribers stations, their condition and voltage ran be aecertained and if all current is supplied from central as in my prior applications, Serial, Number 699,023, filed lzi'arch 13, 192 1, and Serial Number 722,993, filed June 28, 192%, then the resistance of the circuits and their proper tuning can be determined. i

runconnecting subscribers wires or studio s to truni; lines for direct or telephonic connnmication the radio perator has cord smear circuits and terminals of the lines, symbolized at P J J etc, in Fig. t and may have equivalent. automatic: or semiautomatic switching apparatus. The operation is symbolized in Fig. 1,. which shows J and J by means of which the subscriber A can be trunked to. any part: of the system. without going through the telephone switchboard. I have shown the subscribefis radio receiving set in Fig. i as provided with an exten sion telephone T-t, and by means of these and. the separate switching apparatus under control of the radio operators it is to be understood that all radio operations, includ ing in telephone trunking or interconnection between. radio subscribers can be handled by the radio switchboard, without access to the telephone switchboard or the telephone operators, (except in cases where the same switchboard is employed for both classes of service )j I believe this to b original with me and shall claim. the same accordingly. The typical and preferred mooe of trunking by wire in this system, however, is by means of modulated superaudio frequency carrier current which can be interchangeably in'iposed on the wired circuits upon suitable radio frequency carrier waves so as to render transn'iission and oi the mixed s3 stem both simple and flexible. This is accomplished; by first of all modulating the seconda'y intermediate frequ-ncy in accordance i i h the sounds which it desired to transmit;and' then sending this modu circ are appropriately tuned. as indicated in 5,6 and 7. It 18. also to be undc ood that when transmitted over long trunlzs. the carrier currents may be relayed and amplified and may be passed through filter circuits when required, all according to principles which are well understood in t, and which have not been illustrated as they form no part of the present inw-ition. Tiltifj, for example, in assuming s. nnection from the head B stations in ig. l to the master station A, it

alien for granted that the wire trunk employed for this purpose may be multiplexed and provided with tube relays and amplifiers, the same at present. If more i e frequency isassigned o the r dio broadcasting: corporation for use (in W of carrier current might be confined by agreement to the same trunk or trunks,'or if more flexible I cement were possible.

if u; might be applied over any trunks in .the I a detail of admimst-ration. to be: worked out and agreed upon between This i system.

change over and between the elements ed trunk lines, all such frequencies the telephone company and the broadcasting company; but the principles involved of having certain frequencies or bands of frequencies which can be separately allotted for radio uses only over a. system of. wired trunk lines, I believe tov be original with me and shall claim the same accordingly. This is not to be confused with telephone trunking broadly, even though it be employed for transmitting sounds from a distance to a radio broadcasting studio. The combination I present is more flexible than that, and at the same time more comprehensive, because it includes all the Elll'llltS of an. organized system, whereby modulated intermediate carriers may be forwarded either by means of Wires or by means of double modulated carrier Waves, from any point in the system to any othercpoint in the system, without losses or distortion due: to changes in frequency or tuning. It will be remem bered that for receiving purposes the instruments atsubscribers stations are all sup posed to be standardized and tuned to one lined frequency. (This of course is subject to'distribution of carrier Wave frequencies as expediency may determine and as recommended by the Government. For general purposes it may be assumed here that all subscribers instruments are tuned fixedly for the same primary carrier wave frequency.) Inpassing through the relay stations however, the primary carrier wave, fre quencies, change from A to. B, from B to C, and from C to subscribers D. Thus, if the sending station. B should vary the frequency of the C carrier wave transmitted, this would not affect the intermediate wave frequency or the audio modulations, and so long as C uses the proper frequency F, for the subscribers, the original intermediate Waves formed and modulated at the point of origin, would. be available in the subscribers tuned local circuit.

For metering the service, the arrangement shown. in Fig. 5 is typical of a number of such arrangements that. can be employed, but all of this work is done at the C stations, so far as the. subscribers are concerned. I- do. not specifically claim the metering cir cuits and apparatus herein, thesame being described andclaimed in copending applications, Serial Number 581,831,;filed August 14, 1922, Patent No. 1,522,359, granted Jan. 6., 1925, Serial Number 583,560., filed August 1922. Patent. No. 1,522,367, granted Jan. 6, 1925. Serial Number 691,825, filed February 9, 1924, and Serial Number 7 32,7 97 filed August 18, 1924, Patent No. 1,627,332, granted May 3, 1927.

.ln' Fi, I have shown an automatic commutator g and anoperatmds key g for connecting the meteringgenerator in, the local or cut off circuit 19 to a line taking. radio service, sot-hat. the telephone; line meter LM may be energized at intervals determined by the speed and construction of the commu tator g. By this method, radiophone time use is charged for in telephone call units. The adjustn'ient of relative unit values between the radio use and the telephone use is not attempted as a finality, because it will be determined by some mutual adjustment owing to the necessity for distribution of profits. In other words, if the telephone rates come down because of increased earnings through the radio service, then the rate of charging in telephone call units for radio service will have to be increased, in order to maintain a parity. Such a result is like ly to follow the introduction of combined service, such as herein described.

Where all recording is done on the same meters, as in Fig. 5, it has already been pointed out that reading the meters, record ing, bookkeeping, billing and collecting can all be performed by the same force and at the same expense required for telephone service alone. The savings by this method have also been pointed out. Several other aspects of this point are to be considered. including the metering or recording of service between central stations and the allocation of charges based thereon; the proper division of gross receipts, as between the telephone administration and the radio ad ministration; and the separation of radio and telephone charges in monthly statements to the subscribers when the subscribers demand it, or where it is required by law. These points will be further discussed presently.

The installing, inspecting, testing and maintaining of subscribers station equipment is all for the C stations. It should be pointed out however that where a subscrihers telephone line terminates in a telephone exchange different from that which constitutes or is associated with the C station for that area, maintenance, equipment, testing. etc. would be for the nearest central station. by preference. whether a broadcast ing station or not. There is another reason for this, viz: that the subscriber looks to his own central station for maintenance of his telephone instrument, and it is good practice to unify and not divide in ca es of this kind. For this reason, if the rat 0 administration be in the hands of a separate 'corporation, the actual physical work in connection with the subscribefs station and line equipment. would be in the hands of his local wire exchange. it might be added that to be constant. and in accordance with the I best practice. all subscribers station equipboard instrument equipment from the telephone company. The great advantage of this will appear in connection with the discussion of charges and finance.

As records compiling, editing, and publishing of the radio programs, this is necessarily in the hands ofthe C stations for their respective areas. Nation wide announce ments may be briefly broadcasted over the entire system, local announcements may be similarly broadcasted from B stations and 0 stations respectively; but time, service, and copper are all too valuable in an organized system, to make any suflicient announce ment of regular programs. These should be determined far enough in advance as indicated by the daily dispatch sheets as shown in Figs. 9, 10 and 11, to be interchanged by mail or by wire reports run through at times when the wires are otherwise idle. Artists and performers or lecturers are booked up at A, B and C stations respectively, accord ing to their national, divisional, district or local value. These bookings may be divided into several classes, as for example: (a) permanent attractions, including artists and musical organizations of established standing, lecturers, etc. These have permanent numbers on all the dockets of the A, B and C stations, and can be used in forming permanent programs days, weeks or months ahead. (6) temporary attractions, due to public notoriety, or some other interest. These get star numbers on all dockets, and according to their rank, of national, district or local, they are inserted on programs by A, B or C stations, respectively. (0) news items, and other purely ephemeral matters of interest only at the moment, which are not carried on the dockets, except as blanks to be filled, which blan is however may be given regular numbers for convenience in wire communications. (d) emergencies and disasters of such character as to have the right of way over all other items. These are not booked, but may be carried in blanks as by the press associations. For example, photographs and other materials concerning prominent people, occasions, etc., locations where earthquakes have occurred and may occur again, etc, are kept in order, are kept up to date, and numbered permanently for radio reference. portance, and affairs of the National Government. These cannot be docketed, but are carried with a double star, and preferably given one number which suffices to clear the air and if necessary take over the entire system with or without notice.

From the foregoing, it will be evident that communicz'itioi'l with the subscribers is from the C stations, not only in broadcasting and over telephone lines, but through the press and by the means of advertising. Nevertheless, according to the nature of the items (6) events of national im- All till

demands a division of his radiophone and of his telephone accounts. The simplest method is the best, and that which presents itself as the most available is also one oi the earliest methods of metering known in the telephone art. This is to provide a simple counting device at the subscribers station stepping around a number device or devices as in a Veeder counter. Meters of this sort actuated by the switchhooh of telephone instruments are well known in the art; and a Veeder counter of this type may be attached to any form of. switch adapted to control the radio receiving instrument. By providing this counting instrument with a stepping magnet included in the radio battery circuit from central, a momentary break in the line made simultaneously with the closure of the line meter at the radio switchboard would actuate the subscribers meter so that itwould show the timeuse of his radiophone, in telephone message units. Another method is to apply the counting meter to the sub scribers telephone instrument. instead'ot the radiophone so that it will record his telephone calls in exactly the same manner as the line meter at the central station. To do this. the meter must register additional units for messages exceeding .the three minute or other minimum length of time. which is now quite generally fixed in exchanges throughout the country. One way of accomplishing this is to make the operators key in the tele phone cord circuit of the subscribers answer-- ing operator. momentarilysend high potene tial current from the usual meter generator Gt (see lower part of .Fig. 5).. to lines as well as through the central otlicc meter circuit. To take advantage of this the high wound meter magnet at the subscribers station might be connected across the line while the subscriber is talking only.

Another, and a preferable method if the matter of expense 'be disregarded, is to duplicate the line meters LM (Fig. at the central station, providing each line with one meter for telephone calls, and another meter for radiophone calls or time use. Insuch case the wire 19' would have to be duplicated, so that the radio meter would have its own separate wire loading from the test- .thimbles of the radio jacks J. The twin plug arrangement of Fig. 5 would be eminently suited to this arrangement since the wire 298 would then pass parallel to the wire '19", and connect with the winding 299 on a separate radio. line meter, without other the double cost of maintenance.

Assuming, then, that the two services are separate, but switchboard and other operation requiring technical handling to be in the hands of the wire company, it is obvious that periodical accountings must be had. For this purpose, it is necessary to know the total time use of the radio service of each class, and the total use of the telephone service for the same period. For a general accounting, details would not be necessary. Thus, a message meter of the type LM in Fig. 5, vfor each operators position of the switchboard hereintypi'fied, and having a branch from its coils -299.300 to the meter button of each one of the cord circuits on its position, would record all the telephone calls, including extra charges on that position, it being evident that an operator would not press two meter buttons at the same instant. This is indicated in Fig. 5 at PM, which designates a position meter reading in totals of calls of that position.

Inasmuch as the recording of two classes of service on the same telephone line meter is new, the necessity for distributing charges recorded is also new, and I believe the arrangement thus specified to be originalwith meand shall claim the same accordingly.

Parallel means for metering the total station load may be in the form-ofa Bristol recording time sheet, taken from a station meter connected. in the main bus circuits so as to record the total current consumption for thestation. I propose :to use this principle for a check against the message meter record in effecting settlement between the radio administration and the telephone administration in this system. Telephone use may be ascertained by position meters. :as above stated, and is recorded in message units each equivalent to one three minute conversation. Radio time use might be separately recorded in this'way, using a position meter, or a meter of the type LM for each cord or connective circuit on the radio switchboard. I consider it preferable however to connect a recording ammeter in the main battery bus connectionito :the supervisory lamps (see 10-5 of Fig. '5) or some other piece of apparatus which has a. constant resistance and a constant current How. This is indicated at PM and BM in Figs. 5 to 7 inclusive. I have also indicated in Fig. 3 a station meter to record the total current flow through the lamps s or their shunt circuits for telephone connections. thus making a parallel record to that of the radio service. By plotting the curves thus developed on straight line section sheets, a direct comparison between the total radio time use and the total telephone time use canbe 

